The present invention relates to the general technical field of appliances for assisting in angularly positioning the bones of a joint in order to perform arthrodesis.
The present invention provides a guide for angularly positioning the bones of a joint in order to perform arthrodesis.
In a preferred but non-exclusive application, the angular positioning guide in accordance with the invention is more particularly intended and designed for angularly positioning the metatarso-phalangeal joint, it being understood that applications to other joints, and in particular those of the shoulder, can also be envisaged.
In cases of arthrosis occurring in bone joints, and in particular in the metatarso-phalangeal joint, it is often necessary to perform arthrodesis in order to fuse the two bones together. In general, arthrodesis is a difficult operation since it locks a joint in a defined position in irreversible manner. Thus, arthrodesis of the metatarso-phalangeal joint is of very great importance insofar as this joint is involved in critical manner in the walking cycle of a human being. It will thus be understood that it is essential for the two bones to be positioned relative to each other prior to being fused in an orientation with the best possible accuracy in order to avoid any subsequent impediment.
It is therefore essential to fix the relative axes of the bones so as to comply as well as possible with the flexions and the axes of the patient, and do this as a function of the patient""s sex and morphology.
Until now, metatarso-phalangeal arthrodeses have been performed in relatively empirical manner, with the values for the angles between the metatarsus and the phalanges being determined and fixed in relatively crude manner, with respect to determining both the varus-valgus angle and the dorsiflexion angle of the joint.
In practice, it is found that if the angles selected by the surgeon are poorly complied with during the operation, consequently leading to an incorrect fixing of the fusion axes between the bone, then either the patient is impeded when walking, with the patient consequently compensating by corrective positioning that can itself give rise to secondary troubles, or else the patient has difficulty in putting on and taking off shoes, or indeed suffers from rubbing or irritations that give rise to various sores.
In all cases, failure to comply with fusion angles carefully determined in advance by the surgeon gives rise to consequences that are harmful for the patient who has been subjected to arthrodesis, and these consequences need to be avoided.
A particular object of the invention is to remedy the various drawbacks listed above, and to propose an appliance or guide for angularly positioning the bones of a joint in order to perform arthrodesis.
Another object of the invention is to propose a positioning guide that is particularly adapted to angularly position the metatarso-phalangeal joint in a manner that is simple and reliable.
Another object of the invention is to propose a positioning guide whose initial adjustment and installation are particularly easy.
Another object of the invention is to propose a positioning guide enabling the various axes to be adjusted in a manner that is quick and reliable.
Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled into the art.
These objects given to the invention are achieved by means of a guide for angularly positioning the bones of a joint for the purpose of performing arthrodesis and comprising:
a base for positioning on the joint, and having an adjustment shaft whose position is designed to be adjusted so as to be substantially vertically above a fixed first geometrical reference point of the joint; and
an adjustment assembly mounted to slide axially and in rotation on the adjustment shaft to adjust respectively a height for the assembly relative to the first geometrical reference point and a first angle xcex1 for the assembly about said axis, said adjustment assembly being formed by an angular adjustable member which can be positioned on a graduated piece to adjust a second angle xcex2 centered on the first geometrical reference point, but situated in a plane different from the first angle xcex1.